Hydrocracking is a basic conversion process used in many petroleum refineries worldwide to reduce the molecular weight of petroleum derived feedstocks and convert the feedstock into more valuable products such as motor fuel, diesel fuel and lubricants. Hydrocracking also has other beneficial results such as removing sulfur and nitrogen from the feedstock by hydrodesulfurization. While the overall physical design of a hydrocracking process can be very important to the level of conversion and selectivity achieved by a hydrocracking process, these two measures of performance are always also tied to the abilities of the hydrocracking catalyst employed in the process.
Hydrocracking catalysts are subject to initial classification on the basis of the nature of the predominant cracking component of the catalyst. This classification divides hydrocracking catalysts into those based upon an amorphous cracking component such as silica-alumina and those based upon a zeolite cracking component such as Y zeolite. Hydrocracking catalysts are also subject to classification on the basis of their intended predominant product of which the two main products are naphtha and “distillate”, a term which in the hydrocracking refining art refers to distillable petroleum derived fractions having a boiling point range which is above that of naphtha. Distillate typically includes the products recovered at a refinery as kerosene and diesel fuel. The subject invention relates to a zeolite catalyst having improved selectivity for the production of distillate boiling range hydrocarbons. These catalysts normally comprise a zeolite component and a binder or other component such as alumina or silica-alumina and a metal hydrogenation component.